Process for selectively growing thin metallic film of copper or gold

ABSTRACT

A process for growing a thin metallic film of gold or copper selectively on a predetermined area of a substrate. An organic complex or organometallic compound of gold or copper as a starting material is heated to evaporate the same, while a substrate having on the surface thereof a metal or a metallic silicide as a first material and an oxide or a nitride as a second material is heated at a temperature equal to or higher than the decomposition temperature, on the first material, of a vapor of the starting material. The vapor of the evaporated starting material is fed together with a reducing gas onto the heated substrate to selectively grow a thin metallic film of gold or copper only on the surface of the first material.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for growing a thin metallicfilm and an apparatus therefor. Particularly, the present inventionrelates to a process and an apparatus for growing a thin metallic film,which is well adapted to metallic wiring and interlayer electricalconnection of multi-layer wiring in a semiconductor integrated circuit.

2. Description of the Prior Art

A decrease in the size or width of wirings and an increase in the numberof layers in a semiconductor integrated circuit have been demanded inkeeping with an increase in the scale of integration thereof. A decreasein the size or diameter of holes (contact holes and through-holes) forelectrical connection of wirings between multiple layers has also beendemanded. Under such circumstances, it has been increasingly difficultto fill such holes with a metal according to a conventional method suchas vacuum evaporation and deposition or sputtering. Further, thedecrease in the width of the wiring causes an increase in the currentdensity. A conventional aluminum wiring tends to break due toelectro-migration when the current density increases, or due to stressmigration. Hence, there is a limit to usage of aluminum for wiringmaterial. Tungsten and molybdenum have a high migration resistance buthave such high electric resistance that a semiconductor integratedcircuit in which wirings of tungsten or molybdenum are used cannot beoperated at a high-speed. Accordingly, realization of a method forforming a copper wiring or gold wiring, each of which has a low electricresistance and high migration resistance, by chemical vapor deposition(CVD) is desired. Especially, a selective CVD method by which a hole isselectively filled with copper or gold is strongly desired.

CVD methods for growth of copper are disclosed in U.S. Pat. Nos.2,833,676 and 2,704,728. In the both methods, copper is deposited on thewhole surface of a substrate irrespective of the material of the surfaceof the substrate. Hence, aforementioned methods are not suitable to filla fine hole with copper. Many selective growing methods using CVD havebeen reported as to tungsten, molybdenum and aluminum.

U.S. Pat. No. 3,697,342 discloses a method of selectively growing copperon a substrate according to CVD. In this method, utilization is made ofcompetitive progress of etching of a substrate material along withdeposition of a metal on a substrate. That is, a gas or vapor ofhexafluoroacetylacetonato-copper as a starting material is introducedtogether with hydrofluoric acid or sulfur fluoride as an etching gas into a reaction chamber to simultaneously cause an etching reaction withthe substrate made of boron glass, phosphorus glass or soda glass and acopper deposition reaction on a tungsten, chromium, or silicon oxidefilm formed on the substrate to thereby selectively grow copper on thegiven portion of the substrate.

According to the conventional selective copper growth method asmentioned above, however, the shape of a substrate is changed as copperdeposition proceeds, because utilization is made of competitive progressof etching of the material of the substrate along with the filmdeposition as described above. This results in large inaccuracies of thedimensions of the resulting structure, which cannot match with fineprocessing techniques. Furthermore, according to the conventionalselective growth method, it is impossible to selectively grow a metalinside through-holes or contact holes to effect electrical connectionbetween wirings in multiple layers.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a process forselectively growing gold or copper on a predetermined area of asubstrate.

Another object of the present invention is to provide a process forselectively growing gold or copper, which is well suited to metallicwiring in a semiconductor integrated circuit.

Still another object of the present invention is to provide a processfor selectively growing gold or copper, which is well suited to finemetallic wiring adapted to scale up the integration of a semiconductorintegrated circuit.

A further object of the present invention is to provide a process forselectively growing gold or copper, which is well suited to interlayerelectrical connection of multi-layer wiring in a semiconductorintegrated circuit.

A still further object of the present invention is to provide anapparatus for stably effecting the selective growth of gold or copper.

In the first aspect of the present invention, a process for growing athin metallic film, comprises steps of:

heating an organic complex or organometallic compound of gold or copperas a starting material to evaporate the same;

heating a substrate having on the surface thereof a metal or a metallicsilicide as a first material and an oxide or a nitride as a secondmaterial to a temperature equal to or higher than the decompositiontemperature, on the first material, of a vapor of the starting material;and

feeding the vapor of the evaporated starting material being kept at atemperature lower than the decomposition temperature thereof togetherwith a reducing gas onto the heated substrate to selectively grow a thinmetallic film of gold or cooper only on the surface of the firstmaterial.

Here, the organic complex or organic compound may be at least one memberselected from a group consisting of β-diketonato compounds of copper orgold and cyclopentadienyl compounds of copper or gold.

The organic complex or organometallic compound may be at least onemember selected from the group consisting of bis-acetylacetonato-copper,bis-hexafluoroacetylacetonato-copper, bis-dipivaloylmethanato-copper,dimethyl-gold-hexafluoro-acetylacetonato,cyclopentadienyl-triethylphosphine-copper complex, anddimethyl-gold-acetylacetonato.

The first material may be at least one member selected from the groupconsisting of aluminum, copper, gold, silicon, titanium, tungsten,chromium, molybdenum, zirconium, tantalum, vanadium and silicidesthereof. The second material may be at least one member selected fromthe group consisting of silicon oxide, silicon nitride and titaniumnitride.

The organic complex or organometallic compound may bebis-hexafluoroacetylacetonato-copper, which may be evaporated by heatingat a temperature of 50° to 150° C. to form a vapor thereof, which may bethen fed through a gas ejecting orifice being heated at a temperatureequal to or higher than 50° C. but lower than 200° C. onto the substratebeing heated at a temperature of 250° to 450° C.

The organic complex or organometallic compound may bebis-acetylacetonato-copper or dimethyl-gold acetylacetonato, which maybe evaporated by heating at a temperature of 100° to 150° C. to form avapor thereof, which may be then fed through a gas ejecting orificebeing heated at a temperature equal to or higher than 100° C. but lowerthan 200° C. onto the substrate being heated at a temperature of 200° to450° C.

The organic complex or organometallic compound may bebis-dipivaloylmethanato-copper ordimethyl-gold-hexafluoro-acetylacetonato, which may be evaporated byheating at a temperature of 70° to 180° C. to form a vapor thereof,which may be then fed through a gas ejecting orifice being heated at atemperature equal to or higher than 70° C. but lower than 200° C. ontothe substrate being heated at a temperature of 200° to 450° C.

The organic complex or organometallic compound may becyclopentadienyl-triethylphosphine-copper complex, which may beevaporated by heating at a temperature of 50° to 120° C. to form a vaporthereof, which may be then fed through a gas ejecting orifice beingheated at a temperature equal to or higher than 50° C. but lower than200° C. onto the substrate being heated at a temperature of 200° to 350°C.

In the second aspect of the present invention, a process for growing athin metallic film, comprises steps of:

forming an insulating layer made of an oxide or a nitride on asemiconductor substrate;

forming a hole in a predetermined area of the insulating layer topartially expose the surface of the substrate in an area thereofcorresponding to the predetermined area;

forming on the exposed surface of the substrate a priming layer made ofat least one member selected from the group consisting of aluminum,silicon, titanium, tungsten, chromium, molybdenum, zirconium, tantalum,vanadium, and silicides thereof;

heating an organic complex or organometallic compound of gold or copperas a starting material to evaporate the same;

heating the substrate to a temperature equal to or higher than thedecomposition temperature, on the priming layer, of a vapor of thestarting material; and

feeding the vapor of the evaporated starting material being kept at atemperature lower than the decomposition temperature thereof togetherwith a reducing gas onto the heated substrate to selectively grow a thinmetallic film of gold or copper only on the priming layer.

Here, the process may further comprise, after the step of selectivegrowth of gold or copper, the step of:

forming a metallic layer made of a member selected from the groupconsisting of aluminum, gold and copper on the remaining insulatinglayer and the thin metallic film of gold or copper. The priming layermay be formed on the source/drain region of the semiconductor substrate,and the metallic layer may be a wiring layer while the thin metallicfilm of gold or copper may be a layer serving to electrically connectthe source/drain region to the wiring layer.

The semiconductor substrate may be made of silicon. The semiconductorsubstrate may be made of GaAs. The metallic layer may be formed by achemical vapor deposition method.

The process may further comprise, after the step of formation of themetallic layer, the steps of:

forming a second insulating layer on the metallic layer;

forming a hole in a predetermined area of the second insulating layer topartially expose the metallic layer;

growing a thin metallic film of gold or copper on the exposed surface ofthe metallic layer to fill up therewith the hole; and

forming a second metallic layer on the remaining second insulating layerand the thin metallic film of gold or copper.

Each of the metallic layer and the second metallic layer may be a layermade of a member selected from the group consisting of aluminum, goldand copper, and constituting a middle layer of a sandwich structurecomprising the middle layer sandwiched between two layers each made ofat least one member selected from the group consisting of aluminum,titanium, chromium, zirconium, tungsten, molybdenum, tantalum, vanadium,and silicides thereof.

In the third aspect of the present invention, a process for growing athin metallic film, comprises steps of:

forming a second layer made of an oxide or a nitride on an priming layerserving as a first layer and made of a metal or a metallic silicide;

forming a hole in a predetermined area of the second layer to partiallyexpose the surface of the priming layer in an area thereof correspondingto the predetermined area;

heating an organic complex or organometallic compound of gold or copperas a starting material to evaporate the same;

heating the priming layer together with the second layer to atemperature equal to or higher than the decomposition temperature, onthe priming layer, of a vapor of the starting material; and

feeding the vapor of the evaporated starting material being kept at atemperature lower than the decomposition temperature thereof togetherwith a reducing gas onto the heated priming layer and the second layerto selectively grow a thin metallic film of gold or copper only on theexposed surface of the priming layer.

In the fourth aspect of the present invention, a process for growing athin metallic film, comprises steps of:

forming a first insulating layer on a semiconductor substrate;

forming a hole in a predetermined area of the first insulating layer topartially expose the surface of the substrate;

forming a polycrystalline silicon layer on the remaining firstinsulating layer and the exposed surface of the substrate;

forming on the polycrystalline silicon layer a priming layer made of atleast one member selected from the group consisting of aluminum,titanium, tungsten, molybdenum, chromium, zirconium, tantalum, vanadium,and silicides thereof;

patterning the polycrystalline silicon layer together with the priminglayer;

forming a second insulating layer on the remaining priming layer;

forming a hole in predetermined area of the second insulating layer topartially expose the surface of the remaining priming layer;

heating an organic complex or organometallic compound of gold or copperas a starting material to evaporate the same;

heating the substrate to a temperature equal to or higher than thedecomposition temperature, on the remaining priming layer, of a vapor ofthe starting material; and

feeding the vapor of the evaporated starting material being kept at atemperature lower than the decomposition temperature thereof togetherwith a reducing gas onto the heated substrate to selectively grow a thinmetallic film of gold or copper only on the exposed surface of theremaining priming layer.

Here, the priming layer may be formed on the polycrystalline siliconlayer with a layer of an lectroconductive metallic nitride formedtherebetween.

The priming layer may be formed on the polycrystalline silicon layerwith a layer of an electroconductive metallic nitride and a layer of ametallic silicide formed therebetween.

In the fifth aspect of the present invention, a process for growing athin metallic film, comprises steps of:

forming a first insulating layer on a semiconductor substrate;

forming a hole in a predetermined area of the first insulating layer topartially expose the surface of the substrate;

forming a polycrystalline silicon layer on the remaining firstinsulating layer and the exposed surface of the substrate;

patterning the polycrystalline silicon layer;

forming a second insulating layer on the remaining polycrystallinesilicon layer;

forming a hole in a predetermined area of the second insulating layer topartially expose the surface of the remaining polycrystalline siliconlayer;

forming on the exposed surface of the remaining polycrystalline siliconlayer a priming layer made of at least one member selected from thegroup consisting of aluminum, titanium, tungsten, molybdenum, chromium,zirconium, tantalum, vanadium, and silicides thereof to fill uptherewith the hole;

heating an organic complex or organometallic compound of gold or copperas a starting material to evaporate the same;

heating the substrate to a temperature equal to or higher than thedecomposition temperature, on the priming layer, of a vapor of thestarting material; and

feeding the vapor of the evaporated starting material being kept at atemperature lower than the decomposition temperature thereof togetherwith a reducing gas onto the heated substrate to selectively grow a thinmetallic film of gold or copper only on the surface of the priminglayer.

In the sixth aspect of the present invention, an apparatus for growing athin metallic film, comprises:

a reaction chamber capable of being evacuated;

substrate holding means for holding and heating a substrate, thesubstrate holding means being provided in the reaction chamber;

a starting material container for containing a starting material;

heating means for evaporating the starting material in the startingmaterial container;

gas ejecting means having gas ejecting orifices for ejecting a vapor ofthe starting material together with a reducing gas, the gas ejectingmeans being connected to the starting material container, the gasejecting orifices being provided in a face of the gas ejecting meansconfronted with the substrate holding means inside the reaction chamber;and

heat exchanging means for circulating a heat exchange medium to theproximity of the gas ejecting orifices of the gas ejecting means.

The above and other objects, effects, features, and advantages of thepresent invention will become more apparent from the followingdescription of embodiments thereof, taken in conjunction withaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of an example of theapparatus for growing a thin metallic film, which is used to carry outthe process of the present invention.

FIG. 2 is a model diagram showing conditions under which selectivegrowth is effected according to the present invention.

FIGS. 3A to 3C are cross-sectional views of structures produced in majorsteps of an example of the process of the present invention, accordingto which a wiring guide for electrical connection drawn from asemiconductor substrate is formed.

FIGS. 4A to 4D are cross-sectional views of structures produced in majorsteps of another example of the process of the present invention,according to which multi-layer wirings with electrical connectiontherebetween are formed.

FIGS. 5A to 5D are cross-sectional views of structures produced in majorsteps of still another example of the process of the present invention,according to which multi-layer wirings with electrical connectiontherebetween are formed.

FIGS. 6 and 7 are cross-sectional views of respective multi-layer wiringstructures produced according to the process of the present invention.

FIGS. 8A and 8B are cross-sectional views of structures produced inmajor steps of a further example of the process of the presentinvention, according to which multi-layer wirings with electricalconnection therebetween are formed.

FIG. 9 is a cross-sectional view of another multi-layer wiring structureproduced according to the process of the present invention.

FIG. 10 is a schematic cross-sectional view of an example of theapparatus for growing a thin metallic film according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Examples of the present invention will now be described while referringto the accompanying drawings.

FIG. 1 shows an example of an apparatus for selectively growing a thingold or copper film on a predetermined area or areas of the surface of aspecimen substrate. This apparatus is analogous to a commonreduced-pressure CVD apparatus. A reaction chamber 1 can be evacuatedthrough an evacuation aperture 2 with a pumping system not shown inFIG. 1. A suspector or specimen substrate holder 3 for holding aspecimen substrate 4 with plate springs 5 is provided in the reactionchamber 1. A heater 6 is built in the specimen substrate holder 3, andcan heat the specimen substrate 4 to a predetermined temperature. Astarting material container 7 for containing a starting material 8,consisting of an organic complex or organometallic compound of gold orcopper, is provided on the outside of the reaction chamber 1. A gasejecting panel 9 confronted with the specimen substrate holder 3 insidethe reaction chamber 1 is connected through a pipe 10 and a valve 11 tothe starting material container 7. The gas ejecting panel 9 has numerousfine gas ejecting orifices 12. The starting material container 7, thepipe 10, and the valve 11 are heated to a predetermined temperature witha heater 13, while the gas ejecting panel 9 is heated to a predeterminedtemperature with a heater 14 built therein. Alternatively, startingmaterial container 7 may be set within a thermostat. A reducing carriergas such as hydrogen gas is introduced through a piping 15 into thestarting material container 7. Reference numeral 16 denotes an O-ringand 17 denotes a stand. A vapor of the starting material 8 evaporated byheating in the starting material container 7 is ejected together withthe hydrogen gas through the gas ejecting orifices 12 and fed onto thesurface of the specimen substrate 4 held by the specimen substrateholder 3. It was found through a number of experiments that the vapor ofthe starting material 8 is susceptible to the material of the surface ofthe specimen substrate 4 in such a way that it is decomposed on aspecific material selected from among aluminum, titanium, chromium,zirconium, tungsten, molybdenum, tantalum, vanadium, and silicidesthereof to grow thereon gold or copper, while it is not decomposed onother specific material selected from among metallic oxides, such assilicon oxide, and metallic nitrides, such as silicon nitride andtitanium nitride, to fail to grow thereon gold or copper. This isattributable to a difference in the catalytic action on the reductivedecomposition reaction of the vapor of the starting material 8 with thereducing gas between the two kinds of materials. Accordingly, choice ofthe former kind of material as the material of the surface of thespecimen substrate can realize growth of gold or copper on the wholesurface of the specimen substrate, while the use of the former kind ofmaterial in a predetermined area or areas of the surface of the specimensubstrate and the latter kind of material in the other area of thesurface of the specimen substrate can realize selective growth of goldor copper only on the predetermined area of the surface of the specimensubstrate. In effecting such selective growth, it is important toappropriately set the temperatures of the gas ejecting orifices 12, thatis the gas injecting panel 9, and the specimen substrate 4. FIG. 2typically shows the variation of the state of growth of gold or copperwith the temperatures of the gas ejecting orifice and the specimensubstrate. In the region A wherein the temperature of the gas ejectingorifice 12 is equal to or lower than the solidification andprecipitation temperature Tv of the starting material 8, the vapor ofthe evaporated starting material is solidified on the gas ejecting panel9 to fail to be ejected therethrough in a gaseous form. Therefore, thisregion is a temperature range wherein no growth of gold or copper occursirrespective of the temperature of the specimen substrate 4. In theregion B wherein the temperature of the gas ejecting orifice 12 is equalto or higher than the decomposition temperature Td of the vapor of thestarting material 8, when passing through the orifices 12 the vapor ofthe starting material 8 is decomposed, and gold or copper in an atomicor molecular form then reaches the surface of the specimen substrate 4to grow on the whole surface of the specimen substrate 4 irrespective ofthe materials of the surface of the specimen substrate 4. Therefore, thetemperature of the gas ejecting orifices 12 must be not only higher thanthe solidification and precipitation temperature Tv of the startingmaterial 8 but also lower than the decomposition temperature Td of thevapor of the evaporated starting material 8. On the other hand, when thetemperature of the specimen substrate 4 is lower than the decompositiontemperature Ts of the vapor of the starting material 8 on the specificmaterial on which gold or copper is to be selectively grown, the vaporof the starting material fed onto the surface of the specimen substrate4 does not decompose to fail to grow thereon gold or copper. The regionC corresponds to such a temperature range. Only in the region D whereinthe temperature of the gas ejecting orifices 12 or that of the gasejecting panel 9 is higher than the solidification and precipitationtemperature Tv of an organic complex or organometallic compound of goldor copper as the starting material 8 and lower than the decompositiontemperature Td thereof while the temperature of the specimen substrate 4is at least the decomposition temperature Ts of the vapor of thestarting material when it presents on the specific material on whichgold or copper is to be selectively grown, gold or copper can be grownon the predetermined area of the surface cf the specimen substrate 4.Additionally stated, if the gas ejecting panel 9 is made of a metal suchas aluminum or titanium, the above-mentioned two decompositiontemperatures Td and Ts are substantially equal to each other. In theregion E wherein the temperature of the specimen substrate 4 exceeds theTh and is too high, crystal grains of gold or copper selectively grownon the specimen substrate 4 unfavorably become coarse to provide a roughsurface thereof. The value of Th is not definite. The temperature of thespecimen substrate 4 should be higher than the Ts, but is preferably nothigher than the Ts plus about 200° C. Particularly when the process ofthe present invention is incorporated into a process for producing asemiconductor integrated circuit, it is not preferable to raise thetemperature of the specimen substrate to a high degree.

As a starting material, β-diketonato compounds of copper or gold such asbis-acetylacetonato-copper, bis-hexafluoroacetylacetonato-copper,bis-dipivaloylmethanato-copper, dimethyl-gold-hexafluoro-acetylacetonatoor dimethyl-gold-acetylacetonato or cyclopentadienyl compounds of copperof gold such as cyclopentadienyl-triethylphosphine-copper or a mixturethereof can be used.

EXAMPLE 5

An experiment was carried out, whereinbis-hexafluoroacetylacetonato-copper was used as a starting material forselective growth of copper. Bis-hexafluoroacetylacetonato-coppercontained in the starting material container 7 was heated to 70° C., andthen ejected together with hydrogen gas as a carrier gas from the gasejecting orifices 12 of the gas ejecting panel 9 to be fed onto thesurface of a specimen substrate 4. When the temperature of the gasejecting orifices 12, the temperature of the specimen substrate 4, theflow rate of the hydrogen gas, and the pressure inside the reactionchamber 1 were set to be 150° C., 350° C., 100 ml/min, and 1,000 Pa,respectively, a deposition reaction occurred neither on metallic oxidessuch as silicon oxide nor on metallic nitrides such as silicon nitrideand titanium nitride, while copper grew at a rate of about 100 Å/min onmetals such as aluminum, titanium, tungsten, chromium, molybdenum,zirconium tantalum and vanadium as well as on metallic silicidesthereof. No etching was observed on the surfaces of the materials suchas silicon oxide, silicon nitride and titanium nitride, on which nodeposition of copper occurred. When growth of copper was effected on ametallic oxide film and a metallic nitride film each having at least oneof the above-mentioned metals and metallic silicides located on a givenarea thereof under the same conditions as mentioned above, copperselectively grew only on the metal or metallic silicide at a rate ofabout 100 Å/min. This selective growth was genuine selective growth notinvolving etching of the metallic oxide or nitride film.

When the temperature of the starting material container, the temperatureof the gas ejecting orifice, the temperature of the specimen substrate,the flow rate of hydrogen gas, and the pressure inside the reactionchamber were in the ranges of 50° to 150° C., 50° to 200° C., 250° to450° C., 100 to 1,000 ml/min, and 200 to 5,000 Pa, respectively,selective growth of copper could be effected. When the temperature ofthe gas ejecting orifice exceeded 200° C., copper deposited on the wholesurface of a specimen substrate.

While the above-mentioned ranges of conditions were determined when usewas made of an apparatus comprising a cylindrical reaction chamberhaving a diameter of 30 cm, a specimen substrate holder having adiameter of 20 cm, a gas ejecting panel having a diameter of 20 cm andincluding numerous orifices each having a diameter of 1 mm, a distancebetween the specimen holder and the gas ejecting panel being 5 cm, and astarting material container capable of containing 150 g of a startingmaterial, the flow rate of a gas and the pressure inside a reactionchamber are variable depending on the shape of an apparatus just as inother semiconductor processes.

An analogous reaction can be carried out by setting not only thetemperature of a substrate in the range of 200° to 450° C. but also thetemperature of the starting material container in the range of 100° to150° C. in the case of bis-acetylacetonato-copper as well as dimethylgoldacetylacetona and in the range of 70° to 180° C. in the case ofbis-dipivaloylmethanato-copper as well asdimethyl-gold-hexafluoro-acetylacetonato. In the case ofcyclopentadienyl-triethylphosphine-copper complex, an analogous reactioncan be carried out by setting the temperature of the starting materialcontainer in the range of 50° to 120° C. the temperature of a substratein the range of 200° to 350° C. and the pressure inside the reactionchamber in the range of 500 to 5,000 Pa while using hydrogen gas as acarrier gas to be introduced into the system. The above-mentionedstarting materials may also be used in mixture.

EXAMPLE 2

FIGS. 3A to 3C show an example wherein selective metal growth accordingto the present invention is applied to formation of a wiring guide forelectrical connection drawn from a semiconductor substrate. This examplerelates to formation of a wiring guide for electrical connection drawnfrom the source/drain of a MOSFET.

An insulating layer 19 such as a silicon oxide film is formed on asemiconductor substrate 18 such as a silicon substrate. A hole 19Areaching the surface of the semiconductor substrate 18 is formed in theinsulating layer 19 by a common lithographic method. Subsequently,doping is effected with a dopant to form a source/drain 18A (FIG. 3A).Subsequently, as shown in FIG. 3B, a diffusion barrier layer 20 made oftungsten, molybdenum, titanium, zirconium, chromium, tantalum, vanadiumor a silicide thereof is selectively formed on the exposed surface ofthe doped semiconductor substrate 18A (source/drain) by a known methodsuch as sputtering. Thereafter, as shown in FIG. 3C, gold or copper 21is selectively deposited on the diffusion barrier layer 20 according tothe process as described in Example 1 to fill up therewith the hole. Inthis manner, electrical connection drawn from the predetermined positionof the semiconductor substrate is established through the gold or copper21 grown as a wiring guide. The diffusion barrier layer 20 not onlyserves as a priming layer to allow gold or copper to selectively growthereon, but also plays a role of preventing the gold or copper fromdiffusing into the source/drain.

EXAMPLE 3

FIGS. 4A to 4D show a process for producing a multi-layer wiringstructure by utilizing the process for growing a thin metallic filmaccording to the present invention, as well as a multi-layer wiringstructure produced thereby.

A first wiring layer 22 of aluminum, copper or gold is formed on theinsulating layer 19 and the gold or copper 21 in the hole 19A on thesemiconductor substrate 18 constituting the structure of FIG. 3C whichis produced through the steps of FIG. 3A to 3C (FIG. 4A). Silicon oxideis deposited as an insulating interlayer 23 on the first wiring layer 22and then etched in part to form therein a hole 23A (FIG. 4B) accordingto a common lithographic process. Subsequently, copper or gold 24 isselectively grown inside the hole 23A, that is, on the exposed surfaceof the first wiring layer 22, according to the process as described inExample 1 to fill up therewith the hole 23A to thereby planalize theupper surface (FIG. 4C). Finally, as shown in FIG. 4D, a second wiringlayer 25 of aluminum, copper or gold is formed by a common method. Inthis manner, electrical connection of source/drain 18A--metallic layer21--wiring layer 22--metallic layer 24--wiring layer 25 is establishedto complete multi-layer wiring.

Additionally stated, the first wiring layer 22 and the second wiringlayer 25 can be formed using the apparatus as shown in FIG. 1 accordingto a CVD method. Specifically, an organic complex or organometalliccompound of aluminum, copper or gold as a starting material isevaporated to form a vapor of the starting material, which is thenejected from the gas ejecting orifices heated at a temperature equal toor higher than the decomposition temperature of the starting material togrow aluminum, copper or gold on the whole surface including thesurfaces of insulating layer 19 (23) and the selectively grown gold orcopper 21 (24) to thereby form a film of aluminum, copper or gold, whichmay then be subjected to predetermined patterning if necessary to form awiring layer.

EXAMPLE 4

FIGS. 5A to 5D show an example wherein the process for growing a thinmetallic film according to the present invention is used for electricalconnection of a first wiring layer made of polycrystalline silicon witha second wiring layer made of a metal through an insulating interlayersandwiched between the first and second wiring layers.

As shown in FIG. 5A, polycrystalline silicon 26 is deposited on theupper surface including the surface of a silicon oxide layer 19 and thatof the doped substrate 18A for the purpose of forming an electrode forthe source/drain 18A of a semiconductor substrate 18. Subsequently, apriming layer 27 made of at least one material selected from amongtitanium, tungsten, chromium, molybdenum, zirconium, tantalum, vanadiumand silicides thereof is formed on the resulting polycrystalline siliconlayer 26 according to a common method.

Subsequently, as shown in FIG. 5B, the polycrystalline silicon layer 26and the priming layer 27 are patterned into the form of an electrode,followed by deposition of an insulating layer 23, in which a hole 23A isthen formed.

Thereafter, as shown in FIG. 5C, copper or gold 24 is selectively growninside the hole 23A according to the process as described in Example 1to fill up therewith the hole 23A to thereby planarize the uppersurface.

Finally, as shown in FIG. 5D, a second wiring layer 25 made of a metalsuch as aluminum is formed on the above-mentioned upper surface tocomplete multi-layer wiring.

FIGS. 6 and 7 show other types of multi-layer wiring structures producedby the process of the present invention.

The structure of FIG. 6 is characterized in that a layer 28 of anelectroconductive metallic nitride such as titanium nitride issandwiched between a polycrystalline silicon layer 26 and a metalliclayer 27 just as shown in FIG. 5D to prevent gold or copper 24 fromdiffusing downwardly to thereby improve the reliability of thestructure. The metallic nitride layer 28 is made by depositing a metalsuch as titanium on the polycrystalline silicon and nitriding itaccording to the common method.

The structure of FIG. 7 is characterized in that a surface portion of apolycrystalline silicon layer 26 as shown in FIG. 6 is converted into ametallic silicide layer 29 by a common alloying method to lower theelectric resistance of the structure.

Where the polycrystalline silicon layer 26 and the priming layer 27conducive to the selective growth cannot be simultaneously patterned inthe step as shown in FIG. 5B, the following procedure may be takeninstead. As shown in FIG. 8A, a polycrystalline silicon layer 26 ispatterned into the form of an electrode, followed by formation thereonof an insulating interlayer 23, in which a hole 23A is then formed.Thereafter, a priming layer 30 made of aluminum, titanium, tungsten,molybdenum, chromium, zirconium, tantalum, vanadium or a silicidethereof is formed on the exposed surface of the remainingpolycrystalline silicon layer 26 by a known method. Thereafter, as shownin FIG. 8B, copper or gold 24 is selectively grown inside the remaininghole 23A according to the process as described in Example 1.

EXAMPLE 5

FIG. 9 shows a multi-layer wiring structure which is further improved inperformance over the wiring structure of FIG. 4D. A difference of thestructure of FIG. 9 from that of FIG. 4D is that wiring layers 31 ofcopper, gold or aluminum are each sandwiched between layers 32 ofaluminum, titanium, chromium, zirconium, tungsten, molybdenum, tantalum,vanadium or a silicide thereof. The layers 31 and 32 are formed by a CVDmethod. Electrical connection between the wiring layers is made usingcopper or gold 24 selectively grown according to the aforementionedprocess of the present invention.

Where aluminum is used as a wiring material, direct contact thereof withselectively grown gold or copper 24 forms an alloy having a highelectric resistance through a heat treatment. The formation of such analloy can be prevented by using at least one of titanium, chromium,zirconium, tungsten, molybdenum, tantalum, vanadium and silicidesthereof as the material of the layers 32 because the above-mentionedmaterials can prevent upward and downward diffusion of aluminum.

Where copper or gold is used as a wiring material, a decrease inelectric resistance and an improvement in migration resistance can beachieved, and hence enables any one of aluminum, titanium, chromium,zirconium, tungsten, molybdenum, tantalum, vanadium and silicidesthereof to be used as the material of the priming layers conducive tothe selective growth of copper or gold 24. In this case, further, thepriming layers 32 serve to improve the adhesion of the wiring layers 31to an insulating interlayer 23 and to prevent the corrosion of copper ifused.

While only a portion of a MOSFET around the source/drain region thereofis shown in every one of FIGS. 3A to 3C, 4A to 4D, 5A to 5D, 6, 7, 8A,8B, and 9, the applicability of the present invention is not limitedthereto and it will be apparent that the present invention is widelyapplicable to formation of wirings in semiconductor devices. As for thesemiconductor substrate as well, the process of the present invention isnot limited to a combination with a silicon substrate, but can be usedin combination with compound semiconductor substrates including GaAssubstrates.

FIG. 10 shows an embodiment of the apparatus for selective metal growthaccording to the present invention. A heat exchange medium such as asilicone oil is circulated from a heat exchanger 33 through pipings 34and 35 to the proximity of the gas ejecting orifices 12 of a gasejecting panel 9. The temperature of the gas ejecting panel 9 confrontedwith a heated specimen substrate 4 is liable to vary by radiation orheat conduction from the specimen substrate 4. However, the circulationof the heat exchange medium heated at a constant temperature of, forexample, 150° C. with the heat exchanger 33 shown in FIG. 10 can keepthe temperature of the gas ejecting orifices 12 constant to enable goldor copper to be stably grown for a long period of time.

As described above, according to the present invention, a thin film ofgold or copper can be formed in self-alignment with the aid of thematerial of a priming layer different from that of other layertherearound. Accordingly, the process of the present invention can beused to fill up fine, deep contact holes and/or through holes with ametal in wiring of a semiconductor device, and hence can realize anincrease in the scale of integration of wiring patterns as well as adecrease in the capacity thereof. Further, the process of the presentinvention can contribute to planarization of contact portions.Furthermore, according to the present invention, a low electricresistance can be provided as compared with those of tungsten andmolybdenum as used in conventional selective growth, a high speed can berealized with minimizing the time-delay attributed to wirings, andmulti-layer wiring is made easily possible by selective growth of goldor copper on aluminum or titanium, on which the selective growth ofaluminum is difficult, to thereby enable the scale of integration of asemiconductor device to be raised. As described above, the utilizationof the present invention can realize an increase in the scale ofintegration of a semiconductor device as well as speedup thereof.

Other embodiments will be apparent to those skilled in the art fromconsideration of the specification and practice of the inventiondisclosed herein. It is intended that the specification and examples beconsidered as exemplary only, with a true scope of the invention beingindicated by the following claims.

What is claimed is:
 1. A process for growing a thin metallic film,comprising the steps of:maintaining a substrate, having on the surfacethereof a first material consisting of metal or a metallic silicide anda second material selected from the group consisting of silicon oxide,silicon nitride and titanium nitride, under a reduced pressure; heatingan organic complex or organometallic compound of gold or copper as astarting material to evaporate the same; heating said substrate to atemperature equal to or higher than the decomposition temperature, onsaid first material, of a vapor of said evaporated starting material;and feeding a gas stream consisting essentially of the vapor of saidevaporated starting material being kept at a temperature lower than thedecomposition temperature thereof and a reducing gas onto said heatedsubstrate to selectively grow a thin metallic film of gold or copperonly on the surface of said first material.
 2. A process for growing athin metallic film as claimed in claim 1, wherein said organic complexor organic compound is at least one member selected from a groupconsisting of β-diketonato compounds of copper or gold andcyclopentadienyl compounds of copper or gold.
 3. A process for growing athin metallic film as claimed in claim 2, wherein said organic complexor organometallic compound is at least one member selected from thegroup consisting of bis-acetylacetonato-copper,bis-hexafluoroacetylacetonato-copper, bis-dipivaloylmethanato-copper,dimethyl-gold-hexafluoro-acetylacetonato,cyclopentadienyl-triethylphosphine-copper complex, anddimethyl-gold-acetylacetonato.
 4. A process for growing a thin metallicfilm as claimed in claim 1, wherein said first material is at least onemember selected from the group consisting of aluminum, copper, gold,silicon, titanium, tungsten, chromium, molybdenum, zirconium, tantalum,vanadium and silicides thereof.
 5. A process for growing a thin metallicfilm as claimed in claim 3, wherein said organic complex ororganometallic compound is bis-hexafluoroacetylacetonato-copper, whichis evaporated by heating at a temperature of 50° to 150° C. to form avapor thereof, which is then fed through a gas ejecting orifice beingheated at a temperature equal to or higher than 50° C. but lower than200° C. onto said substrate being heated at a temperature of 250° to450° C.
 6. A process for growing a thin metallic film as claimed inclaim 3, wherein said organic complex or organometallic compound isbis-acetylacetonato-copper or dimethyl-gold-acetylacetonato, which isevaporated by heating at a temperature of 100° to 150° C. to form avapor thereof, which is then fed through a gas ejecting orifice beingheated at a temperature equal to or higher than 100° C. but lower than200° C. onto said substrate being heated at a temperature of 200° to450° C.
 7. A process for growing a thin metallic film, comprising thesteps of:heating a starting material consisting ofbis-dipivaloylmethanato-copper ordimetyl-gold-hexafluoroacetylaacetonato at a temperature of 70° to 180°C. to evaporate the same; heating a substrate having on the surfacethereof a metal or a metallic silicide as a first material and an oxideor a nitride as a second material to a temperature of 200 ° to 450° C;feeding the vapor of said evaporated starting material through a gasejecting orifice being heated at a temperature equal to or higher than70° C. but lower than 200° C. together with a reducing gas onto saidheated substrate to selectively grow a thin metallic film of gold orcopper only on the surface of said first material.
 8. A process forgrowing a thin metallic film comprising the steps of:heating a startingmaterial consisting of cyclopentadienyl-triethylphosphine-copper at atemperature of 50° to 120° C. to evaporate the same; heating a substratehaving on the surface thereof a metal or a metallic silicide as a firstmaterial and an oxide or a nitride as a second material to a temperatureof 200° to 350° C; feeding the vapor of said evaporated startingmaterial through a gas ejecting orifice being heated at a temperatureequal to or higher than 50° C. but lower than 200° C. together with areducing gas onto said heated substrate to selectively grow a thinmetallic film of copper only on the surface of said first material.
 9. Aprocess for growing a thin metallic film, comprising steps of:forming aninsulating layer made of an oxide or a nitride on a semiconductorsubstrate; forming a hole in a predetermined area of said insulatinglayer to partially expose the surface of said substrate in an areathereof corresponding to said predetermined area; forming on the exposedsurface of said substrate a priming layer made of at least one memberselected from the group consisting of aluminum, silicon, titanium,tungsten, chromium, molybdenum, zirconium, tantalum, vanadium, andsilicides thereof; heating an organic complex or organometallic compoundof gold or copper as a starting material to evaporate the same; heatingsaid substrate to a temperature equal to or higher than thedecomposition temperature, on said priming layer, of a vapor of saidstarting material; and feeding the vapor of said evaporated startingmaterial being kept at a temperature lower than the decompositiontemperature thereof together with a reducing gas onto said heatedsubstrate to selectively grow a thin metallic film of gold or copperonly on said priming layer.
 10. A process for growing a thin metallicfilm as claimed in claim 9, further comprises, after said step ofselective growth of gold or copper, the step of:forming a metallic layermade of a member selected from the group consisting of aluminum, goldand copper on the remaining insulating layer and said thin metallic filmof gold or copper.
 11. A process for growing a thin metallic film asclaimed in claim 10, wherein said priming layer is formed on thesource/drain region of said semiconductor substrate, and wherein saidmetallic layer is a wiring layer while said thin metallic film of goldor copper is a layer serving to electrically connect said source/drainregion to said wiring layer.
 12. A process for growing a thin metallicfilm as claimed in claim 11, wherein said semiconductor substrate ismade of silicon.
 13. A process for growing a thin metallic film asclaimed in claim 11, wherein said semiconductor substrate is made ofGaAs.
 14. A process for growing a thin metallic film as claimed in claim11, wherein said metallic layer is formed by a chemical vapor depositionmethod.
 15. A process for growing a thin metallic film as claimed inclaim 10, further comprises, after said step of formation of saidmetallic layer, the steps of:forming a second insulating layer on saidmetallic layer; forming a hole in a predetermined area of said secondinsulating layer to partially expose said metallic layer; growing a thinmetallic film of gold or copper on the exposed surface of said metalliclayer to fill up therewith said hole; and forming a second metalliclayer on the remaining second insulating layer and the thin metallicfilm of gold or copper.
 16. A process for growing a thin metallic filmas claimed in claim 15, wherein each of said metallic layer and saidsecond metallic layer is a layer made of a member selected from thegroup consisting of aluminum, gold and copper, and constituting a middlelayer of a sandwich structure comprising said middle layer sandwichedbetween two layers each made of at least one member selected from thegroup consisting of aluminum, titanium, chromium, zirconium, tungsten,molybdenum, tantalum, vanadium, and silicides thereof.
 17. A process forgrowing a thin metallic film, comprising steps of:forming a second layermade of an oxide or a nitride on an priming layer serving as a firstlayer and made of a metal or a metallic silicide; forming a hole in apredetermined area of said second layer to partially expose the surfaceof said priming layer in an area thereof corresponding to saidpredetermined area; heating an organic complex or organometalliccompound of gold or copper as a starting material to evaporate the same;heating said priming layer together with said second layer to atemperature equal to or higher than the decomposition temperature, onsaid priming layer, of a vapor of said starting material; and feedingthe vapor of said evaporated starting material being kept at atemperature lower than the decomposition temperature thereof togetherwith a reducing gas onto said heated priming layer and said second layerto selectively grow a thin metallic film of gold or copper only on theexposed surface of said priming layer.
 18. A process for growing a thinmetallic film, comprising steps of:forming a first insulating layer on asemiconductor substrate; forming a hole in a predetermined area of saidfirst insulating layer to partially expose the surface of saidsubstrate; forming a polycrystalline silicon layer on the remainingfirst insulating layer and the exposed surface of said substrate;forming on said polycrystalline silicon layer a priming layer made of atleast one member selected from the group consisting of aluminum,titanium, tungsten, molybdenum, chromium, zirconium, tantalum, vanadium,and silicides thereof; patterning said polycrystalline silicon layertogether with said priming layer; forming a second insulating layer onthe remaining priming layer; forming a hole in predetermined area ofsaid second insulating layer to partially expose the surface of saidremaining priming layer; heating an organic complex or organometalliccompound of gold or copper as a starting material to evaporate the same;heating said substrate to a temperature equal to or higher than thedecomposition temperature, on said remaining priming layer, of a vaporof said starting material; and feeding the vapor of said evaporatedstarting material being kept at a temperature lower than thedecomposition temperature thereof together with a reducing gas onto saidheated substrate to selectively grow a thin metallic film of gold orcopper only on the exposed surface of said remaining priming layer. 19.A process for growing a thin metallic film as claimed in claim 18,wherein said priming layer is formed on said polycrystalline siliconlayer with a layer of an electroconductive metallic nitride formedtherebetween.
 20. A process for growing a thin metallic film as claimedin claim 18, wherein said priming layer is formed on saidpolycrystalline silicon layer with a layer of an electroconductivemetallic nitride and a layer of a metallic silicide formed therebetween.21. A process for growing a thin metallic film, comprising stepsof:forming a first insulating layer on a semiconductor substrate;forming a hole in a predetermined area of said first insulating layer topartially expose the surface of said substrate; forming apolycrystalline silicon layer on the remaining first insulating layerand the exposed surface of said substrate; patterning saidpolycrystalline silicon layer; forming a second insulating layer on theremaining polycrystalline silicon layer; forming a hole in apredetermined area of said second insulating layer to partially exposethe surface of said remaining polycrystalline silicon layer; forming onthe exposed surface of said remaining polycrystalline silicon layer apriming layer made of at least one member selected from the groupconsisting of aluminum, titanium, tungsten, molybdenum, chromium,zirconium, tantalum, vanadium, and silicides thereof to fill uptherewith said hole; heating an organic complex or organometalliccompound of gold or copper as a starting material to evaporate the same;heating said substrate to a temperature equal to or higher than thedecomposition temperature, on said priming layer, of a vapor of saidstarting material; and feeding the vapor of said evaporated startingmaterial being kept at a temperature lower than the decompositiontemperature thereof together with a reducing gas onto said heatedsubstrate to selectively grow a thin metallic film of gold or copperonly on the surface of said priming layer.